This study aims to investigate the impact of multiple preoperative antihyperstensive drug use on the burden of post-induction hypotension (PIH) in patients undergoing elective cardiac surgery. The researchers will observe whether the combination of different antihypertensive classes (such as ACE inhibitors, ARBs, beta-blockers, and calcium channel blockers) leads to a higher incidence and severity of blood pressure drops and increased need for vasoactive support during the period between anesthesia induction and surgical incision.

Post-induction hypotension (PIH) is a critical period in cardiac anesthesia that can lead to organ hypoperfusion. This prospective observational study will include patients aged 18-85 with ASA III-IV physical status scheduled for elective cardiac surgery.

Preoperatively, patients' chronic antihypertensive medications will be recorded and categorized. Following standard anesthesia induction, hemodynamic parameters will be monitored using invasive arterial blood pressure measurement. PIH burden will be defined as the area under the curve (AUC) for a mean arterial pressure (MAP) lower than 65 mmHg. Additionally, the study will record the total dose of ephedrine or other vasoactive agents required to maintain hemodynamic stability. The primary goal is to determine if multiple antihypertensive therapy is an independent risk factor for increased PIH burden and to compare the effects of different drug combinations on early intraoperative hemodynamics.

Inclusion Criteria:

• Adult patients aged 40 years and older
• Undergoing elective cardiac surgery (e.g., isolated CABG, isolated valve surgery, or combined CABG+valve surgery via sternotomy)
• Regular use of at least one antihypertensive medication for at least 4 weeks prior to the operation date
• Voluntary participation and signed informed consent

Exclusion Criteria:

• Emergency surgery
• Preoperative shock or requirement for high-dose inotropic/vasopressor therapy
• End-stage liver or kidney failure
• Uncontrolled hypertension
• Difficult intubation or prolonged induction process
• Ejection fraction less than 35%

Adult patients (40 years and older) who are scheduled for elective cardiac surgery under general anesthesia at a single tertiary center and have been on a stable regimen of one or more antihypertensive medications for at least one month preoperatively.

De-identified individual participant data underlying the results reported in this article will be available after publication to researchers who provide a methodologically sound proposal.